Fault alarm system



June 6, 1961 J. PoLYzoU FAULT ALARM SYSTEM 4 Sheets-Sheet 1 Filed Sept. l2. 1957 June 6, 1961 .1. PoLYzoU FAULT ALARM SYSTEM 4 Sheets-Sheet 2 Filed Sept. l2, 1957 TERNI/#PNG 557' COMPONENTS ro orf/4 coMMz/A//c'Ar/on/ l//vArre'A/afo .SMT/0N A/f- Inventor .JA/w55 P0 v200 BWM/0%. @am

Attorney June 6, 1961 J. PoLYzou FAULT ALARM SYSTEM 4 Sheets-Sheet 3 Filed Sept. l2, 1957 v c 4 @l o (j man FAI/r $25670@ Sh//rc//fs 3.9

GFA/RAL AZAR O5 C /LLA TOR Inventar JAMES P0( YZO @MZ A torney June 6, 1961 J. PoLYzou FAULT ALARM SYSTEM 4 Sheets-Sheet. 4

Filed Sept. l2, 1957 9 6M 0 m R 0 0 R 0 Y. R r Z A AA AA@ #wm BPH m R Y Y MA m D0, d A 1 n 0 3 o R 7 M Y 2 2 3 A 0.0,. m v J 1 l 1 BP/ E on f 0 .W PPLILPPLTLHV- 8 4 .JlllJll-.l Jl .Il |.ll. Il J I, e 2 m .a C .d a R 6 B 6 c lv A mm A x/AAVAGAA G caca@ o o G c o n M WJ M A7 1 9 0550 Mm.. e/Nsro Mx A 5mm, 3 9 3! A. l 4 4 aNocqo o e o oaooco o o o o o M 0 A A A A 8 6 6 h o e .lili!li!li.!|.|.l.l.l. F J t 3 W i Bv M 3 llm TFM Tm o .n ml WA me md Il 2 A A /A A A 3 0 F 0 F 0 j.. FW A W MAA A ttorney United States Patent O 2,987,712 FAULT ALARM SYSTEM James Polyzou, Nutley, NJ., assignor to International Telephone and Telegraph Corporation, Nutley, NJ., a corporation of Maryland Filed Sept. 12, 1957, Ser. No. 683,655 3 Claims. (Cl. 340-213) This invention relates to an improved system for detecting, transmitting and translating identification of and binary information relating to each of a plurality of sources, and particularly to a fault warning system for use in a communication service channel.

In the past, communication systems employing one or more unattended repeater or remote stations have made use of separate communication channels for transmission of fault and alarm information requiring a relatively large amount of equipment to detect faults, code them for transmission, then decode, sort and display the information at an attended terminal station. Some prior fault and alarm systems of this nature have employed a multiplicity of different tone generators each generating a different tone and each tone indicating the occurrence of a different fault conditionpat a remote station. These systems have also employed at the attended terminal station a separate receiver for each fault tone and a separate indicator for each fault condition.

An object of this invention is to provide an improved system for detecting, transmitting and translating information relating to the general location, specific location and condition of each of a plurality of components.

Another object of this invention is to provide an improved fault and alarm system to accomplish detection, transmission and translation of fault information with a reduction of equipment over prior systems while performing all the necessary functions of such a system.

Another object of this invention is to provide a fault alarm system employing individual tones for fault identication and transmission of fault information using only a single receiver to decode the information.

Another object of this invention is to provide a fault warning system in which failures in the fault warning system itself are indicated with no additional equipment,

In accordance Iwith a feature of this invention, individual `tone `generators are provided, each generating a different tone and each controlled by a different fault condition. When a given fault condition occurs, its associated tone generator ceases to operate and its tone is not added to the service channel line. '-Ihus the absence of the tone is noted at an attended terminal on the same service channel line, and an associated indicator at the attended terminal is energized signifying that the fault has occurred.

In accordance with a further vfeature of this invention, a different general alarm tone is generated at each unattended station. When a fault occurs at a given unattended station, that stations general alarm tone generator ceases lto operate and its general alarm tone is not fed to the service channel line. Thus the failure of one or more fault tone generators at a given unattended station, where actually no fault conditions have occurred, can be detected at an attended station by an observer who -notesthat although fault conditions are indicated by the absence of their associated fault tones from the service channel line, the' general alarm tone is not absent and the failure must be in one or more fault tone generators. This fail-safe feature allows detection of failures in 'the Vfault signaling system itself without the Vrequirement of additional equipment.

In accordance with another feature of this invention,

fcachfault condition -at cache-unattended station, -upon Patented June 6, 1961,

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being detected and decoded at the attended terminal, is indicated by a separate indicator. Thus a different indicator is provided for each fault condition. Each indicator `is energized when its associated fault condition occurs, by a dierent gas triode or thyratron which is caused to re when the associated fault tone is not detected at the attended terminal. When red, the thyratron continues to conduct, energizing its indicator until the operator recognizes the fault condition and de-energizes the indicator by pressing a reset switch, thereby preparing it for subsequent monitoring.

In accordance with another feature of this invention, a diiferent visual indicator is provided at the attended terminal for each of the general alarm tones. Each of these indicators is energized when its associated general alarm tone is not detected at the attended terminal and each remains energized until its associated general alarm tone is again detected at the attended terminal. An audible alarm is also provided at the attended terminal which is energized when any of the general alarm tones are not detected for a given minimum period of time and remains energized until all general alarm tones are again detected. Thus a visual indication of a fault occurrence at each unattended station is provided at the attended terminal in conjunction with an audible alarm which operates only when one or more fault conditions at one or more unattended stations has persisted 'for a given minimum period.

The above-mentioned and `further objects of this invention will be more apparent from the following particular application made with reference to the accompanying drawings, in which:

IFIG. 1 is a block diagram of a fault detection and indication system for detecting faults at unattended stations and monitoring them at an attended terminal;

vFIG. `2 is a detailed block diagram of the fault detection system at an unattended station shown in FIG. l;

PIG. 3 is a detail schematic diagram of the diode switching and thyratron circuits of FIG. 2; and

FIG. 4 is a Idetailed block diagram and electrical schematic of the fault monitoring and indicating system at the attended terminal of FIG. 1.

Referring first to FIG. 1, there is shown a communication service channel line 1 along which are located two unattended repeater stations, station A, designated as 2 and station B, designated as 3, and an attended terminal 4. Information relating to yfailures or faults at station A Iand station B is transmitted over service channel line 1 in the frequency range from 2500 to 3500 c.p.s., while frequencies below 2500 c.p.s. carry speech information over the service channel. The speech information is transmitted at voice Ifrequencies up to 2500 c.p.s. Each unattended repeater station is equipped with a fault detection system capable of detecting up to, for example, eight fault conditions. When these faults occur, they are displayed at attended terminal 4. A different tone frequency is assigned to each of the eight fault conditions at one unattended repeater station and eight other different tone frequencies are assigned to the eight fault conditions at the other unattended repeater station, one to each fault. These tone frequencies originate from the associated Ifault detector and tone generators 5 and 6. High pass lters 7 and 8 at station A and 9 and 10 at station B pass the fault tone frequencies to service channel line y'1. These fault tone frequencies also pass through high pass filter 11 and from there to attended terminal 4 where they are decoded and fault conditions indicated. These high pass `filters block speech frequenci. Unattended repeater sta- Y 3 2500 c.p.s. are blocked from terminating sets 12 and 13 by llow pass lters 14 and 15, and 16 and 17, respectively. These low pass filters passfspeech frequencies from a serviceV channel transmitter toV terminating sets '12 and 13` and on to a service channel receiver after passing through low pass lter 18, which also onlypasses frequencies below 2500 c.p.s. Speech frequencies could also be transmitted over line 1 by a carrier frequency ofrabout 6,000 c.p.s. or higher instead Vof by voiceY frequencies -as described herein. This type transmission is often referred to as carrier telephony. However, ifa carrier kfrequency were employed, the system of high passrand low pass filters described herein and representedv by lters 7, 8, 9, 10, 14, 15, 16, 17, 18 and 11 would have to be altered to achieve the effects described herein. In addition to the eight different fault tones generated at unattended station A and the other eight tones generated at unattended station B, there is a dilerent ninth frequency or characteroscillator 43 by applying a lground voltage to it thus removing'the characteristic general alarm vtone for the Vunattended repeater station from service channel -line 1. Diode switch bank circuit 41 is so designed that the occurrence of any one of the eight fault conditions deactivating an appropriate fault tone oscillator also serves to deactirvate general alarm oscillator 43.A

In FIG. 3 there is shown a detailed electrical schematic of diode switch bank 41 and thyratron circuit 42. Each of istic general yalarm tone generated at each station whose Y absence is indicative of a fault condition having occurred at its associated station. Absence of a general,V alarm tone causes a visual and an audible alarm to be actuated at attended terminal 4 indicating that a fault has occurred at a given unattended repeater station. At attended terminal 4, band pass lter 19 andand band pass filter 20 pass general alarm tones indicative of no failures at station A and station B, respectively.V These general alarm tones are detected Yat detectors 21 and 22, respectively. Upon detection of their associated general alarm tones, these detectors energize relays 21a and 22a which in turn maintain in de-energized conditions alarm'lights 23 and 24, respectively, and audible alarm 25,. When detectors 21 and 22 fail to detect the general alarm tone from stations A and B, respectively, or whenthese detectors themselves fail, relays 21a and 22a respectively, are not energized and alarm lights 23 land 24, respectively, are energized. When not actuated, either of relays 21a or 22a apply power to time delay relay 26, which upon being energized for a given minimum. period of time applies power to audible alarm 25. All theincoming fault condition tones from unattended stations A and B are applied to mixer 27 in whichany single one of them may be beat against the output of step controlled local oscillator 28 to produce abeat frequency of 1200 c.p.s. which passes through a sharply tuned, 1200 cycle band pass filter 29 to rectifier 30. The output of rectifier 30 actuates relay 31 which controls applicationV of striking voltage from battery 32 through sixteen terminal rotary switch 33 and from there to a given fault indicator in fault indicators 34. Manually operated or remotely controlled fault selector 35 is mechanically coupled to sixteen terminal rotary switch 33 and to sixteen terminal rotary switch 36. Switch 36 applies a selected capacitance from capacitance bank 37 to local oscillator 28' causing itrto operate at a frequency which when mixed with a selected fault tone produces a 1200 c.p.s. beat frequency which serves to actuate the given fault detectors 39 applies a ground to diode switch bank 41 when its associated fault occurs and thus to one of individual fault diodes 44 whose outputs are coupled and fed to the control grid of thyratron 45. When no ground from any of fault detectors 39 is appliedrto thyratron 45, the thyratron grid is so biased from |-250 volt D.C. source that it conducts when 335 volt lA.C. source causes its plate to swing positive energizing A.C. relay 46 and thus removing ground from general alarm oscillator A43, allowing the oscillator to operate. Relay V46 is shown in the de-energized position which occurs 'whenever a fault condition existsat the station and the grid of thyratron 45 is grounded. Y Y

Referring now to FIG. 4, there is shown a detailed sche- Y matic of the fault decoding and display system at attended terminal 4. In this figure rotary switches 33 and 36 are shown in linear fashion to facilitate representation and four of the identical, fault-indicator circuits in fault ndicator 34 are shown wired to rotary switch 33. The terminals for each fault in rotary switch 33 are designated by the same letter combinations as applied to the fault indicators. In capacitance bank 37 there is shown sixteen capacitances, each connected to a different terminal in rotary switch 36 and thence to ground. The sixteen terminals of rotary switch 36 are identified in the same manner as opposing terminals on rotary switch 33, and manual operation of these switches from a single manual control mechanically coupled to each connects local oscillator 28 with a given terminal on rotary switch 36 and connects striking voltage lead lineV 38 to an identically marked fault indicator in fault indicators 34 as described above. Referring now to FIG. 2, there is shown a detailed schematic of the fault detection system at unattended repeater station A. The system at unattended repeater station B is identical to this. Each of fault detectors 39 applies aground toa different one of tone frequency oscillators `40 when associated faults occur, thereby deactivating the oscillators. These oscillators are -normally in operation when no faults exist, each transmitting a characteristic fault'tone spaced approximately 55 c.p.s. apart in the frequency range of 2500 to 3500 c.p.s. For example, application of `a ground by yfault detectorr39a to oscillator 40a occurs when fault Aaoccurs (fault a at station A), thus removing the characteristic tone indicative of that fault condition from service channel line 1. When any fault occurs and ground is applied to the associated oscillator, ground is also applied through diode switch bank '41" to thyratron circuit 42,' which deactivates general alarm given terminal in rotary switch 33. In operation, application of a given capacitance from capacitance bank 37 to local oscillator 28 causes it to oscillate at such a frequency that when mixed in mixer 27 witha given fault tone, a 1200 c.p.s. beat frequency is produced. This 1200 c.p.s. signal when rectified servesv to actuate relay'31 so that 4it does not apply striking voltage to theappropriate terminal in rotary switch 33 and thus to gas triode 47a, Which does not re and does not energize neon lamp 48a'.` If the fault tone frequency is absent from'service Vchannel'line 1, indicatingY that a fault has occurred, mixer 27 will not produce a 1200 c.p.s. beat frequency and relay 31 will not be energized, thus striking voltage from battery 32 will 'applied to gas triode 47a causing' it` to fire, lighting neon .lamp 48a andy indicating that-a fault has occurred. Once gas triode 47a tires, it continues to conduct, even though striking voltage is removed at switch`33, andwhile itconducts, neon lamp 48a ,remains lit. Reset switch 49 is provided to clear all the fault display for the purpose of confirming the displays or for restoring the indicator circuits by simply removing B+ from the gas triode in each fault indicator. The operator is thus made aware that all faults at a given unattended repeater stationV have been corrected when the appropriate general alarmlight and buzzer are de-energized.

This invention is particularly useful where it is desired to employ a minimum of equipment'to detect and monitor faults and also provide fail-safe operation of the faultdetection and monitoring system without the requirement of additional equipment. This invention and all its features are also applicable where speech frequencies Vare transmitted by a carrier frequency as in carrier telephony in which application a few minor changes in lterrnetjwork, readily made by one versedinthe art, would be necessary. if

-While there is described above afparticular'example and embodiment of my invention, it is to be clearly understood that this is given merely by Way of example and is not to be considered as a limitation on the scope of my invention as set -forth in the objects and accompanying claims.

I claim:

1. A system for conveying and translating binary information relating to each of a plurality of devices l0- cated at a plurality of stations comprising a plurality of stations, a plurality of devices at each station, a plurality of sources of different signals at each station, a diierent common signal source at each station, means coupling each device at a station with a different one of said sources of diiferent signals and with said common source also at the same station so that each of said different sources of signals is controlled by a dilerent one of said devices and said common signal source is controlled by any one of said devices, variable receiving means for sequentially detecting said different signals, detection means to detect said common signals, means coupling said receiving means with said sources of different signals, means coupling said detection means with said sources of common signals, means to indicate detection of each of said different signals, means to indicate detection of each of said common signals, sequential control means coupled to said receiving means and to said means to indicate detection of said different signals so that said different signals are detected in a sequential manner and indicated singly, and means coupling said detection means and said means to indicate detection of said common signals so that said means to indicate detection of said common signals are controlled by said means to detect said common signals.

2. A fault alarm system for detecting and transmitting fault information relating to each of a plurality of faults occurring at one or more unattended stations on a communication line and receiving and translating said fault information at an attended terminal on the same communication line comprising a communication line, one or more unattended stations on said line, an attended terminal on said line, one or more fault detectors at each unattended station, one or more different tone generators at each unattended station, each generating a different fault tone, means coupling each of said fault detectors at a given unattended station with a different one of said tone generators at the same unattended station so that detection of a given fault causes a given tone generator to cease operation, a general alarm tone generator at each unattended station, each generating a diierent general alarm tone, means coupling each of said fault detectors at a given unattended station with the general alarm tone generator at the same station so that the occurrence of any detected fault at that station causes said general alarm tone generator to cease operation, means coupling the output of each fault tone generator and the output of each general alarm tone generator with said communication line, tunable receiving means at said detection station for sequentially detecting said diiferent fault tones, filter means at said detection station to detect said general alarm tones, means coupling said receiving means and said detection means with said communication line, means for sequentially tuning said receiving means to each of said fault tones, a pluralityof fault indicators, each indicating a different fault, selection means coupling said means for sequentially tuning with said receiving means and coupling the output of said tunable receiving means with said fault indicators so that a given one of said plurality of fault indicators is energized when said receiving means is tuned to a given fault tone and said given fault tone is not detected, general alarm indicators at said attended terminal, and means coupling said lter means With said general alarm indicators so that each of said indicators is energized only when its associated general alarm tone is not detected by said lter means.

3. A fault alarm system according to claim 2, in which each of said plurality of fault indicators is comprised of a thyratron controlled by the output of said receiving -means and said selection means, a visual indicator, and means coupling said thyratron and said visual indicator whereby the visual indicator is energized by the output of the thyratron.

References Cited in the tile of this patent UNITED STATES PATENTS 2,393,021 Cheek Jan. 15, 1946 2,494,370 Swartzel Jan. 10, 1950 2,546,307 Johnson Mar. 27, 1951 2,605,340 Disney July 29, 1952 2,668,283 Mullin Feb. 2, 1954 2,730,579 Case Ian. 10, 1956 2,764,754 Garfield Sept. 25, 1956 OTHER REFERENCES Publication I, Electronics, March 1945, page 132. 

